Portable air filtration unit



FIG. 1 is a perspective view taken from the front _and left side of a portable air filtration unit showing _my new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a front elevational view thereof;

FIG. 5 is a right side elevational view thereof; and

FIG. 6 is a top plan view thereof. 

The ornamental design for a portable air filtration unit, as shown and described. 